Magnetic core



Nov. 25, 1930. J. J. VIENNEAU MAGNET I C CORE Filed Dec. 23, 1929 H i s Attorn ey.

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Inventor. Jacobdvienneau, y Maw/ Fig.1.

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Patented Nov. 25, 1930,

UNITED STATES PATENT OFFIE $3.803 J. VIENNEAU, OF PITTSFIELD, MASSACHUSETTS, ASSIG'NOR T GENERAL ELEC- TRIO COMPANY, A CORPORATION OF NEW YORK MAGNETIC CORE Application filed December 23, 1929. Serial No. 415,901.

My invention relates to laminated magnetic cores for electrical induction apparatus such as transformers and reactors and its general object is to provide an improved method for producing magnetic laminations for such cores.

The iaininations used in magnetic cores are cut or punched from large stock sheets which are produced by a rolling process from bars or billets of a suitable magnetic material such as silicon steel or a magnetic nickel iron alloy. The rolling process produces a grain in the sheets, this grain extending in the direction in which the sheets have been rolled, and it has been found that the best results are obtained if the laminations are arranged so that their grain extends in the direction of the flux path in all parts of the core. In many magnetic cores, however, it has been found desirable and convenient to use L- shaped punchings in forming the core laminations. It is o vious that the grain cannot extend longitudinally of both parts of an Lshaped punching which is taken integrally item a stock sheet because the grain extends in the same direction in all parts of the sheet while the two parts of an L-shaped punching are at right angles to each other. The general object of the invention is to pro vide an improved method for producing integral magnetic L-shaped punchlngs or 1mmnation sections with the grain extending longitudinally throughout both parts of the punching and therefore in the direction of the flux 11th in a magnetic core including such Fig. 6 shows a simple form of magnetic core including punchings formed in accordance with the invention.

Like reference characters indicate similar parts in the difierent figures of the drawing.

50 The strips 10 and 11 shown respectively in Figs. 1 and 2 are of thin magnetic material such as silicon steel or a magnetic nickel iron alloy and are produced by the usual rolling process from bars or billets so that the strips have a granular structure, the grain extending longitudinally of the sheets and in parallel to their side edges. The strips may be of any desired widths and of indefinite lengths. They may, for instance, be formed by welding together end to end a number of shorter strips as indicated by the Welds 12.

The strips 10 and 11 are cut or sheared into sections along the oblique lines 13. This separates the strip 10 into a plurality of sections 14 and the strip 11 into a plurality of sections 15, each of the sections 14 and 15 having parallel side edges 16 and oblique parallel end edges 17. The cutting or shearing apart of the sections 14 and 15 along the lines 13 may be straight cuts as indicated in Fig. 5 or at least part of them may be of saw tooth character so that at least one of the oblique end edges of each section will be of saw tooth formation as indicated in Figs. 3 and 4.

A section 14 from the strip and a seclion from the strip 11 are placed together in the relative positions indicated in Figs. 3. 4 and 5, one of the obliquc end odgcs 17 of each section abultiug an oblique cud edge 17 of the other section. The abutting cdgcs 17 of the two sections l4 and 15 are tlicu welded together to form a unit. The lines 13 and therefore the cuts which sever the sections 14 and 15 make complementary acute angles with the side edges of the strips 10 and 11 so that the side edges 16 and the grain of the two sections 14 and 15 when welded together as described are respectively at right angles.

The welded units are cut or sheared along the broken lines 18 of Figs. 4 and 5, these broken lines being parallel to the edges 16 and meeting at the weld between the sections 14 and 15 of the unit. The welded unit is thus separated into L-shapcd members of the desired shape and size for use in building up magnetic cores such as is shown in Fig. 6. After each L-shapcd member is severed from the remainder of the welded unit, its outer ends may be trimmed ofi' to fit better into the core. Fig. 5 shows one of the L-shaped members severed from the remainder of the welded unit and with its outer ends trimmed oil.

It will be obvious that the size and proportions of the L-shaped members may be predetermined as desired. For instance, the lengths of the, two parts or legs of the L- shaped members are determined by the spacing of the lines 13 in the strips and 11 respectively. The relative widths of the two legs of the L-shaped members are determined by the obliquity of the lines 13 with respect to the side edges of the strips 10 and 11. Thus, by decreasing the oblique anglebetween the lines 13 and the side edges of the strip 10 and correspondingly increasing the oblique angle between the lines 13 and the side edges of the strip 11, the longer leg of each L-shaped lllell'lbel' will be narrower with respect to the shorter leg. If the oblique angles between all the lines 13 and the side edges of both 7 strips 10 and Ham equal to forty-five degrees, then the widths of the two legs of each L-shaped member will be equal. In this latter case, of course the two sections 14 and 15 which are welded together may both be cut or severed from the same strip.

The invention provides a convenient and economical method for producing L-shaped lamination sections or members for magnetic cores and has the further advantage that the grain of the material extends longitudinally of both parts or legs of each L-shaped section and therefore in the direction of the magnetic flux path in all parts of the finished core.

The invention has been explained by describing and illustrating certain steps which may be followed but it will be apparent that changes ma be made in the method without departing rom the spirit of the inventionor from the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. The method of producing L-shaped magnetic core lamination members, said method including the, steps of severing two sect-ions from magnetic strip sheet material along lines making acute complementary angles with the side edges of said strip material, welding said sect-ions together end to end with their side edges respectively at right angles, thus forming a welded unit, and severing L-shaped members from said unit along lines parallel to the side edges of the sections of the unit and meeting at the weld.

2. The method of producing L-shaped magnetic core lamination members, said method including the steps of severing two sections from rolled magnetic strip sheet material having a grain in the direction in which the strips were rolled, said sections being severed along lines making acute complementary angles with the direction of the In witness whereof, I have hereunto set.

my hand this 19th day of Dee, 1929.

JACOB J. VIENNEAU. 

